Growth medium

About: Growth medium is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 59171 citations. The topic is also known as: culture medium & culture media.

Evidence for osmoregulation of cell growth and buoyant density in Escherichia coli.

Abstract: The buoyant density of cells of Escherichia coli B/r NC32 increased with the osmolarity of the growth medium. Growth rate and its variability were also dependent upon the osmolarity of the medium. Maximum growth rates and minimum variability of these rates were obtained in Luria broth by addition of NaCl to a concentration of about 0.23 M.

Growth characteristics af low Na+ concentration and the stability of the Na+ requirement of a marine bacterium

Abstract: Studies of the marine bacterium Alteromonas haloplanktis 214 (formerly referred to as marine pseudomonad B-16) showed that as the Na+ concentration in the growth medium decreased from 230 to 34 mM, the lowest concentration permitting growth, the length of the lag period preceding exponential growth increased. Once growth had begun, except for a slight reduction in rate of growth at 34 mM Na+, the generation time and extent of growth remained essentially constant over the range of Na+ concentrations tested. Plate counts showed that during the lag period the numbers of viable cells introduced as inoculum into a complex medium containing 33 mM Na+ decreased exponentially before increasing. Repeated subculture of the cells at 33 mM Na+ failed to eliminate the lag period or reduce the loss of viability of the cells. The viability loss and the lag period could be eliminated either by raising the NaCl concentration to 130 mM or by adding sufficient sucrose to make the osmotic pressure of the medium equal to that obtained by adding 130 mM NaCl. In a chemically defined medium, sucrose added to maintain tonicity reduced but did not eliminate the lag periods obtained at suboptimal Na+ concentrations. Increasing the number of cells plated on trypticase agar medium reduced the Na+ concentration required to permit growth. Evidence was obtained of a requirement of A. haloplanktis for Ca2+ for growth. Ca2+ spared to a small extent the requirement for Na+ for growth. Some 10(10) cells of a histidine-requiring, streptomycin-resistant mutant of A. haloplanktis 214, still viable after treatment with N-methyl-N'-nitro-N-nitrosoguanidine, were screened for capacity to grow in the absence of Na+. Since no non-Na+-requiring mutants were isolated, the requirement of this organism for Na+ would appear to be extremely stable.

Enzymatic properties of lipase and characteristics production by Lactobacillus delbrueckii subsp. bulgaricus.

Abstract: Some properties of an extracellular lipase produced byLactobacillus delbrueckii subsp.bulgaricus were studied. Maximum enzyme activity was found against olive and butter oil as enzyme substrates. Addition of 9% acacia gum, 0.1% Na-deoxycholate and 0.01 M CaCl2 to the enzyme reaction mixture increased-lipase activity from 5.3 to 14.5 (FFA/mg protein/minute) at pH 6.0 and at 40° C. Maximum lipase production was reached in the presence of glucose as a sole source of carbon, wheat bran as nitrogen source, olive oil as a sole lipid source and butyric acid as fatty acid supporting the growth medium. An initial pH value of the culture medium of 6.0 and a temperature of 35° C gave the highest lipolytic activity.

Influence of Culture Media on the Radiation Resistance of Micrococcus radiodurans

Abstract: The addition of NZ-case (a tryptic digest of casein) to a growth medium (PC) consisting of tryptone, glucose, and yeast extract caused a significant decrease in γ radiation resistance of Micrococcus radiodurans. The level of radiation resistance was inversely related to the concentration of NZ-case. The ld50 for this organism was approximately 700 krad when grown in tryptone, glucose, yeast extract, and dl-methionine (TGYM) broth, but it was approximately one-half as resistant when grown in a PC medium containing 0.5% NZ-case (PCNZ). The resistance to ultraviolet light was also reduced. Cultures transferred from PCNZ to TGYM media regained the high level of resistance.

Variation in the growth medium during the culture cycle of Tetrahymena: with special reference to ammonia (NH3), ammonium (NH4+), and pH1.

Abstract: The ciliate Tetrahymena pyriformis was grown in a peptone medium without added glucose. The interrelationship between increasing cell density and pH of the growth medium was studied from mid-log to the stationary phase, i.e. from 50,000 to 1,000,000 cells/ml, by continuous registration of the pH of the growth medium. The present findings correlate with the known physiological, biochemical, and structural changes occurring in Tetrahymena as it passes through the culture cycle. The ammonia production of the cells and the buffer capacity of the growth medium were determined throughout the growth cycle. The results revealed that the ammonia excreted by the cells can explain the increase in pH of the medium from 6.8 to about 8.3 normally seen during the culture cycle. Moreover, neither the increased pH nor the raised level of ammonia were found to be the responsible factor for cessation of cell proliferation in the stationary growth phase although these factors may affect cell proliferation in concentrations well beyond the range found in normal cultures.